CN115092941A - Method for recovering residual carbon and sodium silicate from coal gasification fine ash by using low-temperature alkali fusion method and application - Google Patents
Method for recovering residual carbon and sodium silicate from coal gasification fine ash by using low-temperature alkali fusion method and application Download PDFInfo
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Abstract
A method for recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method and application thereof belong to the technical field of industrial solid waste treatment. The invention aims to solve the problems that high-value utilization of coal gasification fine ash is difficult to realize in the prior art, and the problems that the temperature is too high and the residual carbon is burnt and lost in the traditional alkali fusion method are solved. The method comprises the following steps: firstly, preprocessing; secondly, alkali fusion; thirdly, water immersion treatment; the application comprises the following steps: the low modulus sodium silicate solution is used for preparing water glass or white carbon black, and the residual carbon is used for preparing active carbon. The invention relates to a method for recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method and application thereof.
Description
Technical Field
The invention belongs to the technical field of industrial solid waste treatment.
Background
Coal gasification technology produces syngas (CH) by incomplete oxidation of coal 4 CO, etc.), which have made important contributions to clean utilization of coal resources and coal chemical industry in recent years. With the widespread use of coal gasification technology, the production of coal gasification fine ash is also rapidly increasing (about 3000 ten thousand tons/year). However, the existing treatment method has low economic benefit, so that the existing treatment method of the coal gasification fine ash still mainly adopts stockpiling and burying, and cannot realize resource utilization, which causes the problems of waste of coal resources and serious environmental pollution.
In the treatment of the coal gasification fine ash, the existing special method mostly adopts physical methods such as flotation, gravity separation and the like to realize carbon ash separation. In the patent of flotation process for coal gasification fine slag (patent number: 201610261413.4, application publication date: 2017, 10 and 31 days, application publication number: CN107303539A), 500g/t of potassium persulfate, 100g/t of ferrous sulfate heptahydrate, 5000g/t of diesel oil and 5000g/t of sec-octanol are respectively used for realizing recovery of carbon resources in coal gasification fine ash by utilizing the hydrophobicity difference of the surfaces of different composition minerals, but the use amount of a flotation agent is too large, so that the problems of high operation cost and overproof content of organic pollutants in flotation return water exist. In the patent of the method for preparing the adsorbing material by using the coal gasification fine slag and the prepared adsorbing material (the patent number is 201710154400.1, the granted publication date is 10 and 11 days in 2019, and the granted publication number is CN 107855103B), a carbon-rich product is obtained through gravity cyclone separation, and the value of the adsorbing product is improved by using hydrothermal activation to prepare the adsorbing product, but the coal gasification fine ash has small particle size and small density difference between carbon particles and ash particles, so that the separation efficiency is low. HF treatment, the most efficient method for deashing at present, can result in a final ash content of less than 5%. However, HF acid has strong corrosivity and high toxicity, not only is the process dangerous to some extent, but also the deashing waste liquid is difficult to treat and is easy to cause secondary pollution, and the large-scale application cannot be realized only in a laboratory.
SiO in coal gasification fine ash 2 High content, and the alkali fusion method can realize high-efficiency silicon recovery. In the patent of a method for synchronously synthesizing zeolite and LDH by taking fly ash as a raw material (the patent number is 201810906032.6, the granted publication date is 8/6/2021, and the granted publication number is CN109107526B), the ash minerals are efficiently digested by alkali fusion treatment at 850 ℃, the ash minerals are converted into soluble silicate, the silicate products are collected by hydrothermal treatment, and a raw material is provided for preparing zeolite. However, the traditional alkali fusion treatment temperature is higher (550-1000 ℃) and far higher than the ignition point of the coal gasification fine ash (460-530 ℃), and the residual carbon has combustion loss. Therefore, how to realize the high-efficiency deashing of the coal gasification fine ash is a difficult problem which is urgently needed to be solved for the resource and harmless treatment of the coal gasification fine ash on the basis of ensuring the recovery rate of carbon in the coal gasification fine ash.
The coal gasification fine ash contains a large amount of amorphous silica and can be used for preparing water glass to realize high-value treatment of coal gasification. In patent "a method for preparing high-modulus water glass by using fly ash" (patent number: 201811395302.8, application publication date: 2019, 2, 15 and application publication number: CN109336123A), the fly ash and sodium hydroxide are mixed, high-temperature alkali fusion treatment is carried out at 1400 ℃, ash minerals are converted into soluble silicate, and then water immersion is carried out to successfully prepare a water glass product, but because the treatment temperature reaches 850 ℃, molten NaOH has strong corrosivity and has higher requirement on the corrosion resistance of equipment. Patent simultaneous preparation of SiO by using fly ash 2 Aerogel and zeolite preparation method (patent number: 200910010685.7, application publication date: 2009, 9, 23, application publication number: CN101538046) by activating fly ash at 600-900 deg.c, hydrothermal reacting with NaOH solution, and washing filtrate to obtain SiO by normal pressure drying method 2 An aerogel. In conclusion, the traditional alkali fusion method for preparing the water glass has overhigh temperature and larger energy consumptionIn order to reduce the cost of preparing the water glass by gasifying the fine coal ash.
Meanwhile, the coal gasification fine ash has high ash content, is mostly amorphous silicon dioxide with high reaction activity, and has the potential of serving as a raw material of white carbon black. In patent "method for extracting high-purity alumina and silica gel from fly ash" (patent number 201010013749.1, publication authorization date: 2012, 12 and 5 days, publication authorization number: CN101759210B), the fly ash and Na are mixed 2 CO 3 Mixing and successfully converting ash minerals in the fly ash into soluble silicate through the steps of high-temperature roasting (700-1000 ℃), NaOH leaching, selective separation and the like, so that a high-quality raw material is provided for preparing the white carbon black, but the treatment temperature is higher, the reduced pressure distillation energy consumption is higher, and the problem of higher cost exists. According to the patent, silicon in the fly ash is dissolved out in the form of sodium silicate through NaOH high-pressure hydrothermal treatment (patent number 200710062534.7, publication date granted: 6/9/2010, publication number granted: CN101125656B), and the white carbon black is prepared by utilizing a carbon method. At present, because the carbon content of the coal gasification fine ash is high (10-50%), if the white carbon black is prepared by a hydrothermal method, the dosage of acid and alkali can be increased due to the porous structure with rich residual carbon, the cost is increased, and the complete recovery of Si resources in the coal gasification fine ash cannot be realized. The traditional alkali fusion preparation process has high treatment temperature (above 800 ℃), and a large amount of heat energy needs to be input in the preparation process, so that the waste of porous carbon resources in the coal gasification fine ash is caused.
Disclosure of Invention
The invention aims to solve the problems that high-value utilization of coal gasification fine ash is difficult to realize in the prior art, and combustion loss of residual carbon exists due to overhigh temperature in the traditional alkali fusion method, and further provides a method for recovering the residual carbon and sodium silicate from the coal gasification fine ash by using a low-temperature alkali fusion method and application thereof.
The method for recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method comprises the following steps:
firstly, preprocessing:
removing metal impurities in the coal gasification fine ash, and drying to obtain a sample after impurity removal;
secondly, alkali fusion:
mixing the sample after impurity removal with solid alkali, then carrying out alkali fusion treatment for 20 min-3 h at the temperature of 200-450 ℃, and finally taking out the sample and reducing the temperature to room temperature to obtain an alkali fusion original shape;
the mass ratio of the sample after impurity removal to the solid alkali is 1 (0.5-5);
thirdly, water immersion treatment:
soaking the alkali melt in water for 1-10 min at 20-60 ℃ to obtain a water leaching system, carrying out vacuum filtration on the water leaching system, drying the filtered solid to obtain residual carbon, and obtaining low-modulus sodium silicate solution as the filtered liquid;
the mass ratio of the alkali fusion original sample to the water is 1 (1-10).
The application of recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method is characterized in that water glass or white carbon black is prepared by using a low-modulus sodium silicate solution, and activated carbon is prepared by using the residual carbon.
The invention has the beneficial effects that:
1. the invention utilizes an alkali fusion method to recover the residual carbon in the coal gasification fine ash. Compared with the traditional HF acid pickling method, the method is green, environment-friendly, safe and reliable, and compared with the traditional alkali fusion method, the low-temperature alkali fusion treatment used in the method has stronger applicability to the coal gasification fine ash, and can effectively recover the residual carbon. The implementation of the invention not only realizes the high-efficiency recovery of C, Si resources in the coal gasification fine ash (the recovery rate of combustible carbon is as high as 80.65%), but also can be used for preparing porous materials due to the abundant pore structure of the recovered carbon, thereby providing a scheme for the high-value utilization of the coal gasification fine ash. The invention induces the molten alkali to generate targeting reaction with the ash mineral in the coal gasification fine ash by controlling the alkali fusion temperature (200-450 ℃) and the time, so that the ash mineral is converted into soluble salt and the residual carbon is reserved. Then the ash content is less than 3 percent and the specific surface area is 445 after the water immersion treatment.43m 2 A pure carbon sample with 91.26% fixed carbon content and a low modulus sodium silicate solution. The treatment method avoids secondary pollution, and has the characteristics of high safety, short reaction time, easy operation and environmental protection. The implementation of the invention not only realizes the high-efficiency recovery of C, Si resources in the coal gasification fine ash, but also provides a more green scheme for the large-scale treatment and the high-efficiency deashing of the coal gasification fine ash.
2. The invention provides a method for preparing water glass by using coal gasification fine ash. The coal gasification fine ash is used as a silicon source to replace silica gel such as quartz sand, wollastonite and the like with higher price, so that the defects of high raw material cost and high energy consumption of the traditional water glass are overcome. Is beneficial to the large-scale and high-value utilization of the coal gasification fine ash. The coal gasification fine ash is used as a silicon source, and the advantages of the coal gasification fine ash are fully utilized. The method conforms to the basic national policy of national energy conservation and emission reduction, waste resource utilization and sustainable development, and solves the problems of complex preparation process, serious pollution and high cost of the traditional water glass.
3. The invention provides a method for preparing white carbon black from coal gasification fine ash by using an alkali fusion method. The method has low equipment requirement, low energy consumption and low investment, and the nano white carbon black prepared by the method has the average particle size of 20nm and the nitrogen adsorption average specific surface area of 120.9m 2 The/g can be put into commercial use and gasification into raw materials is adopted to solve the dual problems of environmental problem and economic replacement of industrial raw materials. The method has important significance for realizing high-value and sustainable utilization of the coal gasification fine ash.
4. Compared with the traditional activated carbon preparation process, the preparation method does not need HF acid deliming, and no secondary pollution is generated in the preparation process. The specific surface area of the obtained activated carbon product is up to 750m 2 /g～860m 2 (ii) in terms of/g. When the sample is used as the super capacitor activated carbon, the mass specific capacitance reaches 110-125F/g under the current density of 0.5A/g. The method realizes high-value utilization of the coal gasification fine ash, and simultaneously, the activated carbon preparation process is more green, thereby having important significance for improving the activated carbon preparation process.
Drawings
FIG. 1 is a test chart of specific surface area of residual carbon prepared in the first example;
FIG. 2 is an SEM image of silica prepared in example IV;
FIG. 3 is a graph illustrating specific surface area measurements of white carbon black prepared in example four;
FIG. 4 is a cyclic voltammogram of a three-electrode cell prepared with activated carbon at a current density of 0.5A/g, where 1 is AC-Zn-8-4-1, and 2 is AC-H 3 PO 4 -5-4-1；
FIG. 5 is a charge-discharge curve diagram of a three-electrode cell prepared with activated carbon at a current density of 0.5A/g, where 1 is AC-Zn-8-4-1, and 2 is AC-H 3 PO 4 -5-4-1。
Detailed Description
The first embodiment is as follows: the method for recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method comprises the following steps:
firstly, preprocessing:
removing metal impurities in the coal gasification fine ash, and drying to obtain a sample after impurity removal;
secondly, alkali fusion:
mixing the sample after impurity removal with solid alkali, then carrying out alkali fusion treatment for 20 min-3 h at the temperature of 200-450 ℃, and finally taking out the sample and reducing the temperature to room temperature to obtain an alkali fusion original shape;
the mass ratio of the sample after impurity removal to the solid alkali is 1 (0.5-5);
thirdly, water immersion treatment:
soaking the alkali melt in water, soaking the alkali melt in water at the temperature of 20-60 ℃ for 1-10 min to obtain a water soaking system, performing vacuum filtration on the water soaking system, drying the filtered solid to obtain residual carbon, and obtaining low-modulus sodium silicate solution as the filtered liquid;
the mass ratio of the alkali fusion original sample to the water is 1 (1-10).
In the embodiment, the coal gasification fine ash is used as coal-based industrial solid waste, has the characteristics of high yield, high carbon content and rich residual carbon pore structure, the carbon-rich product obtained after complete deashing (ash content is less than 5%) treatment is a high-quality raw material for preparing activated carbon, and compared with the currently mainstream raw material for preparing activated carbon, namely biomass, a carbonization process is not needed in the preparation process. Therefore, the energy consumption for treatment is reduced while achieving high-value and harmless treatment of the coal gasification fine ash.
The beneficial effects of the embodiment are as follows:
1. in the embodiment, residual carbon in the coal gasification fine ash is recovered by an alkali fusion method. Compared with the traditional HF acid washing method, the method is green, environment-friendly, safe and reliable, and compared with the traditional alkali fusion method, the low-temperature alkali fusion treatment used in the embodiment has stronger applicability to the gasified fine ash, and can effectively recover the residual carbon. The implementation of the embodiment not only realizes the high-efficiency recovery of C, Si resources in the coal gasification fine ash (the recovery rate of combustible carbon is as high as 80.65%), but also provides a scheme for the high-value utilization of the coal gasification fine ash by preparing the porous material because the recovered carbon has rich pore structures. The embodiment induces the molten alkali to perform targeted reaction with the ash minerals in the coal gasification fine ash by controlling the alkali fusion temperature (200-450 ℃) and time, so that the ash minerals are converted into soluble salts and residual carbon is reserved. Then the ash content is less than 3 percent and the specific surface area is 445.43m after the treatment of water immersion 2 A pure carbon sample with 91.26% fixed carbon content and a low modulus sodium silicate solution. The treatment method avoids the generation of secondary pollution, and has the characteristics of high safety, short reaction time, easy operation and environmental protection. The implementation of the embodiment not only realizes the high-efficiency recovery of C, Si resources in the coal gasification fine ash, but also provides a more green scheme for the large-scale treatment and the high-efficiency deashing of the coal gasification fine ash.
2. The present embodiment proposes the production of water glass from coal gasification fine ash. The coal gasification fine ash is used as a silicon source to replace silica gel such as quartz sand, wollastonite and the like with higher price, so that the defects of high raw material cost and high energy consumption of the traditional water glass are overcome. Is beneficial to the large-scale and high-value utilization of the coal gasification fine ash. The coal gasification fine ash is used as a silicon source, and the advantages of the coal gasification fine ash are fully utilized. The method conforms to the basic national policy of national energy conservation and emission reduction, waste resource utilization and sustainable development, and solves the problems of complex preparation process, serious pollution and high cost of the traditional water glass.
3. The embodiment provides a method for preparing white carbon black from coal gasification fine ash by using an alkali fusion method. The method has low equipment requirement, low energy consumption and low investment, and the nano white carbon black prepared by the method has the average particle size of 20nm and the nitrogen adsorption average specific surface area of 120.9m 2 The/g can be put into commercial use and gasification into raw materials is adopted to solve the dual problems of environmental problem and economic replacement of industrial raw materials. The method has important significance for realizing high-value and sustainable utilization of the coal gasification fine ash.
4. Compared with the traditional activated carbon preparation process, the preparation method does not need HF acid for deliming, and no secondary pollution is generated in the preparation process. The specific surface area of the obtained activated carbon product is up to 750m 2 /g～860m 2 (ii) in terms of/g. When the sample is used as the super capacitor activated carbon, the mass specific capacitance reaches 110-125F/g under the current density of 0.5A/g. The embodiment realizes high-value utilization of the coal gasification fine ash, and simultaneously, the activated carbon preparation process is more green, and the method has important significance for improving the activated carbon preparation process.
The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: the step one of removing the metal impurities in the coal gasification fine ash is to carry out magnetic separation and iron removal treatment on the coal gasification fine ash under the condition of 8000-12000 gausses. The rest is the same as the first embodiment.
The third concrete implementation mode: this embodiment is different from the first or second embodiment in that: the solid alkali in the step two is NaOH, KOH or Na 2 CO 3 、K 2 CO 3 And Ca (OH) 2 One or a combination of several of them; and in the second step, the atmosphere of the alkali fusion treatment is one or a combination of air, nitrogen, argon and carbon dioxide. The other is the same as in the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: the modulus of the low-modulus sodium silicate solution in the third step is 0.1-0.5. The others are the same as in the first to third embodiments.
The fifth concrete implementation mode: in the embodiment, the application of recovering the residual carbon and the sodium silicate from the coal gasification fine ash by using a low-temperature alkali fusion method is adopted, the water glass or the white carbon black is prepared by using the low-modulus sodium silicate solution, and the activated carbon is prepared by using the residual carbon.
The sixth specific implementation mode is as follows: the fifth embodiment is different from the fifth embodiment in that: when the low modulus sodium silicate solution is used for preparing the water glass, the method specifically comprises the following steps: adding a regulator into the low-modulus sodium silicate solution at room temperature under the stirring condition to obtain water glass; the mass ratio of the low-modulus sodium silicate solution to the regulator is 1 (0.05-0.5); the regulator is one or a combination of several of ammonium nitrate, ammonium sulfate, hydrochloric acid and silicic acid; the modulus of the water glass is 0.5-3.5. The rest is the same as the fifth embodiment.
The seventh embodiment: the difference between this embodiment and one of the fifth or sixth embodiments is that: when the low-modulus sodium silicate solution is used for preparing the white carbon black, the preparation method specifically comprises the following steps:
firstly, adding a regulator into a low-modulus sodium silicate solution at room temperature under a stirring condition to obtain a sodium silicate solution with a modulus of 4-5.5; the mass ratio of the low-modulus sodium silicate solution to the regulator is 1 (0.5-5.5); the regulator is one or the combination of several of ammonium nitrate, ammonium sulfate and silicic acid;
secondly, aging the sodium silicate solution with the modulus of 4-5.5, filtering to obtain a precipitate, washing the precipitate by using deionized water, and finally drying for 4-7 hours at the temperature of 40-60 ℃. The other is the same as the fifth or sixth embodiment.
The specific implementation mode is eight: the difference between this embodiment mode and one of the fifth to seventh embodiment modes is that: the aging treatment in the step II is specifically precipitation for 12 to 72 hours under natural conditions, or hydrothermal treatment for 12 to 24 hours at the temperature of 40 to 60 ℃. The rest is the same as the fifth to seventh embodiments.
The specific implementation method nine: the present embodiment differs from the fifth to eighth embodiment in that: when the carbon residue is used for preparing the activated carbon, the method specifically comprises the following steps: uniformly mixing residual carbon and an activating agent to obtain a mixture, heating the mixture to 500-1000 ℃ under the conditions of specific atmosphere and heating speed of 10-20 ℃/min, activating for 0.5-3 h under the conditions of specific atmosphere and temperature of 500-1000 ℃, placing the activated mixture in distilled water to be washed to be neutral, and performing suction filtration and drying; the mass ratio of the residual carbon to the activating agent is 1 (1-5); the specific atmosphere is water vapor and CO 2 、N 2 And Ar, wherein the specific atmosphere flow is 100 mL/min-1000 mL/min; the activating agent is KOH, NaOH or ZnCl 2 、ZnSO 4 And H 3 PO 4 One or more of them are mixed. The others are the same as the fifth to eighth embodiments.
The specific implementation mode is ten: the difference between this embodiment and one of the fifth to ninth embodiments is that: when the carbon residue is used for preparing the activated carbon, the method specifically comprises the following steps: heating the residual carbon to 500-1000 ℃ under the condition of the atmosphere containing active gas and the heating rate of 10-20 ℃/min, then activating the residual carbon for 0.5-3 h under the condition of the atmosphere containing active gas and the temperature of 500-1000 ℃, placing the activated residual carbon in distilled water to be washed to be neutral, and performing suction filtration and drying; the atmosphere containing the active gas is active gas or the combination of inert gas and active gas; the active gas is water vapor and CO 2 One or a combination of two of them; the inert gas is N 2 And Ar in one or a combination of two; the flow rate of the atmosphere containing the active gas is 100 mL/min-1000 mL/min. The rest is the same as the fifth to ninth embodiments.
The following examples were used to demonstrate the beneficial effects of the present invention:
the first embodiment is as follows:
the method for recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method comprises the following steps:
firstly, preprocessing:
removing metal impurities in the coal gasification fine ash, and drying to obtain a sample after impurity removal;
the coal gasification fine ash is dry ash;
secondly, alkali fusion:
putting the sample after impurity removal and solid alkali into a ceramic mortar, grinding and mixing uniformly, then carrying out alkali fusion treatment for 35min at the temperature of 400 ℃, and finally taking out the sample and reducing the temperature to room temperature to obtain an alkali fusion original sample;
the mass ratio of the sample after impurity removal to the solid alkali is 1: 4.5;
thirdly, water immersion treatment:
soaking the alkali melt in water, performing water leaching for 5min at 40 ℃ to obtain a water leaching system, performing vacuum filtration on the water leaching system, drying the solid after filtration to obtain residual carbon, and obtaining low-modulus sodium silicate solution as the liquid after filtration;
the mass ratio of the alkali fused sample to the water is 1: 8.
The coal gasification fine ash comprises dry ash, ash in water and cake ash, and in the first step, the dry ash is one of the coal gasification fine ash.
In the step one, metal impurities in the coal gasification fine ash are removed, and specifically, the coal gasification fine ash is subjected to magnetic separation and iron removal treatment under the condition of 12000 gauss.
And the solid alkali in the step two is NaOH.
And in the second step, the atmosphere of the alkali fusion treatment is air.
The modulus of the low modulus sodium silicate solution prepared in step three was 0.43.
In the third step, the alkali melt is immersed in water, specifically, the alkali melt is washed into a beaker by using distilled water at 40 ℃.
The recovery rate of combustible (carbon) after the alkali fusion treatment is as high as 80.65%, the ash content is reduced to 2.83% in the residual carbon from 58.93% in the coal gasification fine ash and the fixed carbon content is increased to 91.26% in the residual carbon from 37.55% in the coal gasification fine ash after the alkali fusion treatment, so that the high-efficiency recovery of the residual carbon in the coal gasification fine ash is realized.
FIG. 1 is a test chart of specific surface area of residual carbon prepared in the first example; as can be seen from the graph, the specific surface area of the residual carbon obtained by the recovery was 445.43m 2 Has rich pore structure.
Example two: the water glass is prepared by using the low-modulus sodium silicate solution prepared in the first embodiment, and the preparation method specifically comprises the following steps: adding a regulator into the low-modulus sodium silicate solution at room temperature under the stirring condition, and stirring for 2 hours to obtain water glass; the mass ratio of the low-modulus sodium silicate solution to the regulator is 1: 0.2; the regulator is ammonium nitrate; the modulus of the water glass is 1.21 according to the national standard GB \ T4209-.
Example three: the water glass is prepared by using the low-modulus sodium silicate solution prepared in the first embodiment, and the preparation method specifically comprises the following steps: adding a regulator into the low-modulus sodium silicate solution at room temperature under the stirring condition, and stirring for 2 hours to obtain water glass; the mass ratio of the low-modulus sodium silicate solution to the regulator is 1: 0.2; the regulator is silicic acid; the modulus of the water glass is 3.1 according to the national standard GB \ T4209-.
Example four: when the low-modulus sodium silicate solution in the first embodiment is used for preparing the white carbon black, the preparation method specifically comprises the following steps:
adding a regulator into the low-modulus sodium silicate solution at room temperature under the stirring condition, and stirring for 2 hours to obtain a sodium silicate solution with the modulus of 5.01; the mass ratio of the low-modulus sodium silicate solution to the regulator is 1: 0.5; the regulator is silicic acid;
secondly, aging the sodium silicate solution with the modulus of 5.01, filtering to obtain a precipitate, washing the precipitate by using deionized water, and finally drying for 5 hours at the temperature of 50 ℃ to obtain the white carbon black; the aging treatment in the step II is natural condition precipitation for 48 hours.
FIG. 2 is an SEM image of the white carbon black prepared in the fourth example; as can be seen from the figure, the average particle size of the white carbon black product prepared by the method is about 20nm and reaches the nanometer level.
FIG. 3 is a graph illustrating specific surface area measurements of white carbon black prepared in example four; as can be seen from the figure, the specific surface area of the white carbon black reaches 120.9m 2 /g。
Example five: when the carbon residue prepared in the first embodiment is used for preparing the activated carbon, the method specifically comprises the following steps: uniformly mixing the residual carbon and an activating agent in an agate mortar to obtain a mixture, heating the mixture to 800 ℃ under the conditions of specific atmosphere and heating speed of 15 ℃/min, then activating for 1h under the conditions of specific atmosphere and temperature of 800 ℃, placing the activated mixture in distilled water to be washed to be neutral, and performing suction filtration and drying to obtain activated carbon; the mass ratio of the residual carbon to the activating agent is 1: 4; the specific atmosphere is nitrogen, and the flow rate of the specific atmosphere is 1L/min; the activating agent is ZnCl 2 (ii) a The activated carbon is marked as AC-Zn-8-4-1.
Obtained by a nitrogen adsorption method, and the specific surface area of the activated carbon prepared in the fifth example is 860m 2 /g。
Example six: when the carbon residue prepared in the first embodiment is used for preparing the activated carbon, the method specifically comprises the following steps: uniformly mixing residual carbon and an activating agent in an agate mortar to obtain a mixture, heating the mixture to 500 ℃ under the conditions of specific atmosphere and heating speed of 20 ℃/min, activating for 1h under the conditions of specific atmosphere and temperature of 500 ℃, placing the activated mixture in distilled water to be washed to be neutral, and performing suction filtration and drying; the mass ratio of the residual carbon to the activating agent is 1: 4; the specific atmosphere is nitrogen, and the flow rate of the specific atmosphere is 1L/min; the activating agent is H 3 PO 4 . The activated carbon is noted as AC-H 3 PO 4 -5-4-1。
Obtained by a nitrogen adsorption method, and the specific surface area of the activated carbon prepared in the sixth example is 750m 2 /g。
24mg of AC-Zn-8-4-1 or AC-H 3 PO 4 Uniformly mixing 5-4-1 parts of-5-4-1 parts of 3mg of acetylene black and 3mg of polytetrafluoroethylene according to the mass ratio of 80% to 10%, adding 0.5mL of N-methyl-2-pyrrolidone (NMP) solvent to obtain slurry, and uniformly coating the slurry on a foamed nickel collector (the area is 1 cm) 2 ) The coating mass was about 5 mg. Will coatThe finished electrode was dried in a vacuum oven at 120 ℃ for 12h, cooled to room temperature and then taken out and pressed into a sheet under a pressure of 10MPa to give a sample coated current collector in a three-electrode cell: a platinum sheet was used as the counter electrode, a saturated calomel electrode as the reference electrode, the sample coated current collector as the working electrode, and a 6M KOH solution as the electrolyte.
FIG. 4 is a cyclic voltammogram of a three-electrode cell prepared with activated carbon at a current density of 0.5A/g, where 1 is AC-Zn-8-4-1, and 2 is AC-H 3 PO 4 -5-4-1; FIG. 5 is a charge-discharge curve diagram of a three-electrode cell prepared with activated carbon at a current density of 0.5A/g, where 1 is AC-Zn-8-4-1, and 2 is AC-H 3 PO 4 -5-4-1；
TABLE 1
As can be seen from fig. 4, the prepared activated carbon showed a quasi-rectangular CV curve typical of an electric double layer supercapacitor, indicating that it had good capacitance characteristics. As can be seen from FIG. 5 and Table 1, the mass specific capacitance of the sample obtained from the activated carbon product was 100F/g or more at a current density of 0.5A/g.
Claims (10)
1. The method for recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method is characterized by comprising the following steps of:
firstly, preprocessing:
removing metal impurities in the coal gasification fine ash, and drying to obtain a sample after impurity removal;
secondly, alkali fusion:
mixing the sample after impurity removal with solid alkali, then carrying out alkali fusion treatment for 20 min-3 h at the temperature of 200-450 ℃, and finally taking out the sample and reducing the temperature to room temperature to obtain an alkali fusion original shape;
the mass ratio of the sample after impurity removal to the solid alkali is 1 (0.5-5);
thirdly, water immersion treatment:
soaking the alkali melt in water, soaking the alkali melt in water at the temperature of 20-60 ℃ for 1-10 min to obtain a water soaking system, performing vacuum filtration on the water soaking system, drying the filtered solid to obtain residual carbon, and obtaining low-modulus sodium silicate solution as the filtered liquid;
the mass ratio of the alkali fusion original sample to the water is 1 (1-10).
2. The method for recovering the residual carbon and the sodium silicate from the coal gasification fine ash by using the low-temperature alkali fusion method according to claim 1, wherein the step one for removing the metal impurities in the coal gasification fine ash is to perform magnetic separation and iron removal treatment on the coal gasification fine ash under the condition of 8000-12000 gauss.
3. The method for recovering residual carbon and sodium silicate from coal gasification fine ash by low temperature alkali fusion method according to claim 1, wherein the solid alkali in the second step is NaOH, KOH, Na 2 CO 3 、K 2 CO 3 And Ca (OH) 2 One or a combination of several of them; and in the second step, the atmosphere of the alkali fusion treatment is one or a combination of air, nitrogen, argon and carbon dioxide.
4. The method for recovering residual carbon and sodium silicate from coal gasification fine ash by using low-temperature alkali fusion method according to claim 1, wherein the modulus of the low-modulus sodium silicate solution in the third step is 0.1-0.5.
5. The method for recovering residual carbon and sodium silicate from coal gasification fine ash by low-temperature alkali fusion according to claim 1, wherein the low-modulus sodium silicate solution is used for preparing water glass or white carbon black, and the residual carbon is used for preparing activated carbon.
6. The application of recovering residual carbon and sodium silicate from coal gasification fine ash by using low-temperature alkali fusion method according to claim 5 is characterized in that when the low-modulus sodium silicate solution is used for preparing water glass, the method comprises the following steps: adding a regulator into the low-modulus sodium silicate solution at room temperature under the stirring condition to obtain water glass; the mass ratio of the low-modulus sodium silicate solution to the regulator is 1 (0.05-0.5); the regulator is one or a combination of several of ammonium nitrate, ammonium sulfate, hydrochloric acid and silicic acid; the modulus of the water glass is 0.5-3.5.
7. The application of recovering residual carbon and sodium silicate from coal gasification fine ash by using low-temperature alkali fusion method according to claim 5 is characterized in that when preparing white carbon black by using low-modulus sodium silicate solution, the method comprises the following steps:
firstly, adding a regulator into a low-modulus sodium silicate solution at room temperature under a stirring condition to obtain a sodium silicate solution with a modulus of 4-5.5; the mass ratio of the low-modulus sodium silicate solution to the regulator is 1 (0.5-5.5); the regulator is one or the combination of several of ammonium nitrate, ammonium sulfate and silicic acid;
secondly, aging the sodium silicate solution with the modulus of 4-5.5, filtering to obtain a precipitate, washing the precipitate by using deionized water, and finally drying for 4-7 hours at the temperature of 40-60 ℃.
8. The application of recovering residual carbon and sodium silicate from coal gasification fine ash by using a low-temperature alkali fusion method according to claim 7, wherein the aging treatment in the step (ii) is precipitation for 12 to 72 hours under natural conditions, or hydrothermal treatment for 12 to 24 hours at a temperature of 40 to 60 ℃.
9. The application of recovering carbon residue and sodium silicate from coal gasification fine ash by using low-temperature alkali fusion method according to claim 5 is characterized in that the preparation of activated carbon by using carbon residue comprises the following steps: uniformly mixing the residual carbon and an activating agent to obtain a mixture, heating the mixture to 500-1000 ℃ under the conditions of specific atmosphere and heating speed of 10-20 ℃/min, activating for 0.5-3 h under the conditions of specific atmosphere and temperature of 500-1000 ℃, placing the activated mixture in distilled water to be neutral, filtering, drying and dryingDrying; the mass ratio of the carbon residue to the activating agent is 1 (1-5); the specific atmosphere is water vapor and CO 2 、N 2 And Ar, wherein the specific atmosphere flow is 100 mL/min-1000 mL/min; the activating agent is KOH, NaOH or ZnCl 2 、ZnSO 4 And H 3 PO 4 One or a mixture of several of them.
10. The application of recovering carbon residue and sodium silicate from coal gasification fine ash by using low-temperature alkali fusion method according to claim 5 is characterized in that the preparation of activated carbon by using carbon residue comprises the following steps: heating the residual carbon to 500-1000 ℃ under the condition of the atmosphere containing active gas and the heating rate of 10-20 ℃/min, then activating the residual carbon for 0.5-3 h under the condition of the atmosphere containing active gas and the temperature of 500-1000 ℃, placing the activated residual carbon in distilled water to be washed to be neutral, and performing suction filtration and drying; the atmosphere containing the active gas is the active gas or the combination of inert gas and the active gas; the active gas is water vapor and CO 2 One or a combination of two of them; the inert gas is N 2 And Ar in one or a combination of two; the flow rate of the atmosphere containing the active gas is 100 mL/min-1000 mL/min.
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